1. Field of the Invention
This invention relates to a steam generator for use in a convection oven such as that used in a commercial bakery; and to a heat accumulator unit which forms part of the steam generator.
2. Prior Art
When bread is baked in a convection oven in which the bread is contacted with circulating heated air, it is known to introduce steam or water vapor into the oven chamber for a brief period at the beginning of the baking process to impart a desired color and crispness to the crust of the bread.
In Swiss Pat. No. 532,363, water is sprayed on the walls of steaming chambers heated by circulated air to form steam within the oven chamber.
Swiss Pat. No. 548,161 discloses a steam generator which utilizes an independent heater for the steam generator.
In U.S. Pat. No. 2,767,667, a conveyorized oven has a steaming unit located at the entrance to a conveyor and uses a steam generator which is remote from the conveyor or conveyor housing to provide steam for direct application to the bread. There is a fan for circulating the steam over the entering bread remote from the conveyorized baking area of the convection oven.
U.S. Pat. No. 4,202,259 discloses a nonconveyorized convection oven such as a rack oven which employs a steam generating device outside the oven chamber and which needs no secondary fan for forcing circulation, but which is capable of vaporizing water without the use of any auxiliary heater. The steam generator is described as containing a multiplicity of blocks, which may be in the form of metal balls. The multiple blocks are loosely disposed along a linear channel and heated by circulating heated air. At the beginning of the baking process, water is sprayed onto the blocks where a portion of the water is vaporized while the remainder flows through a slot opening and is distributed over the blocks immediately below.
One of the disadvantages of the steam generator described in U.S. Pat. No. 4,202,259 is that the metal balls are loosely disposed in the generator which makes the generator inconvenient to assemble and repair since loose balls may escape and roll across the factory or bakery floor.